High-pressure fan

ABSTRACT

The invention relates to a high-pressure fan which comprises an electric motor provided with a shaft that goes through it; blade wheels which are mainly made of a carbon fibre-based composite material, arranged on both sides of the electric motor and mounted directly on the shaft of the electric motor; fan housings surrounding the blade wheels; and an intermediate channel which connects a pressure opening of one fan housing to a suction opening of the other fan housing, the intermediate channel being integrated into the base structure of the high-pressure fan.

This application is the US national phase of international applicationPCT/FI02/00885 filed in English on 11 Nov. 2002, which designated theUS. PCT/FI02/00885 claims priority to FI Application No. 20012184 filed12 Nov. 2001. The entire contents of these applications are incorporatedherein by reference.

BACKGROUND OF THE INVENTION

The invention relates to a high-pressure fan which comprises an electricmotor provided with a shaft that goes through it; blade wheels which aremainly made of a carbon fibre-based composite material, arranged on bothsides of the electric motor and mounted directly on the shaft of theelectric motor; fan housings surrounding the blade wheels; and anintermediate channel which connects a pressure opening of one fanhousing to a suction opening of the other fan housing, the intermediatechannel being integrated into the base structure of the high-pressurefan and located substantially below the electric motor and the bladewheels mounted to it.

This type of compact high-pressure fan except for the intermediatechannel structure integrated to the base structure is known from FIpatent 101564. When the blade wheels are made of a mainly carbonfibre-based composite material, the weight of the blade wheel isconsiderably reduced in comparison with the conventional steel andaluminium blade wheels. In spite of this, it has been possible to designthe blade wheels at least as strong as when using the conventionalmaterials. Due to the light weight of the blade wheels, they also do notrequire separate bearings and the bearings of the electric motorsuffice. Due to the light weight of the rotating parts and thepossibility to use smaller slide bearings instead of roller bearings, ithas also been possible to raise considerably the rotation rate of thefan. The first critical rotation rate of the high-pressure fan is at thesame time also at a higher level than that of the conventionalsolutions, which facilitates the use of rotating control in the entirearea of operation, the control being easy to implement by means of afrequency converter.

The two series-connected steps of the high-pressure fan, i.e. theentities formed by each blade wheel and fan housing, are in thissolution according to FI patent 101564 connected to each other by meansof an intermediate channel running over the entire fan structure.

Even though this known high-pressure fan structure provides thesignificant advantages listed above, problems are still caused by saidintermediate channel that requires a lot of space and causes vibrationespecially at high rotation rates.

An intermediate channel structure integrated to the base structure is inturn known from SU invention report 1710849.

BRIEF DESCRIPTION OF THE INVENTION

It is an object of the invention to improve the intermediate channelstructure for use with the high-pressure fan known from FI patent101564. This object is achieved by a high-pressure fan of the invention,which is mainly characterized in that the intermediate channel has,after the pressure opening, a direct channel section for levelling theflow, the length of the section corresponding substantially to thelength of the long side of the pressure opening of the rectangular fanhousing, and that a flow control plate is arranged at the end and in themiddle of the flow-levelling channel section so as to turn the flowsubstantially 90 degrees.

The intermediate channel is placed inside the outlines that it haswithout the intermediate channel of FI patent 101564, since there isfree space for auxiliary equipment inside these outlines, when thisspace and the auxiliary equipment are arranged in a suitable manner.

One advantage of the intermediate channel structure of the invention isa compact, space-saving structure that reduces the need for space on thesite of use as well as freight costs when transporting the fan to thesite of use. An especially high benefit is achieved, when the fan needsto be soundproofed with a soundproof enclosure, since then a lowerstructure also reduces the material costs of the enclosure.

An intermediate channel integrated to the base also adds to the rigidityof the entire fan, thus lowering the vibration level and extending theoperating life. In addition to the rigidity, a lower centre of gravityis also obtained for the structure, whereby these two propertiestogether shift the specific frequencies of the base structure to ahigher frequency range, in other words, provide a wider rotation rateactivity.

The fan can now also be mounted on vibroinsulators instead of directlyon a concrete base, which would otherwise be obligatory due to thecritical specific frequencies. The vibroinsulators, in turn, enable afreer placement of the fan, i.e. not only on the ground floor of abuilding as is usually the case when the fan is mounted directly on aconcrete base.

BRIEF DESCRIPTION OF THE FIGURES

The invention will now be described in greater detail by means of apreferred embodiment and with reference to the attached drawing, inwhich

FIG. 1 shows a general view of a high-pressure fan of the invention, and

FIG. 2 shows the intermediate channel structure of the fan of FIG. 1.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows a high-pressure fan having an electric motor 1 with a rotorshaft 2 that goes through it, i.e. a shaft with its ends protruding fromboth sides of the motor, as its driving power source. A light bladewheel 3 and 4 made at least mainly of a carbon fibre-based compositematerial, i.e. at least the blades 3 a, 4 a and the end plates 3 b, 4 bare made of the material, is directly mounted without separate bearingsto both ends of this shaft 2. The hub structure 4 c of the blade wheelcan also be made of some other material, such as steel. This directmounting means that only the bearings of the electric motor are used inthe mounting of the entire structure described above. The blade wheels 3and 4 are surrounded by fan housings 5 and 6, and a pressure opening 9of the first housing 5 is connected by an intermediate channel 7 to asuction opening 10 of the second housing. The pressure opening of thesecond housing is indicated with reference numeral 11 and the suctionopening of the first housing with reference numeral 12. The entire fanstructure described above is placed on a simple, steel base structure 8.

According to the invention, the intermediate channel 7 is integrated tothe base structure 8 of the high-pressure fan below the electric motor 1and the blade wheels 3 and 4 arranged to it.

According to FIG. 2, the intermediate channel 7 has, after a pressureopening 13 connected to the pressure opening 9 of the first housing 5, adirect channel section 14 for levelling the flow, the length of thesection corresponding substantially to the length of the long side ofthe rectangular pressure opening 9 or 13.

A flow control plate 15 that is curved in the direction of the flow isarranged at the end and in the middle of the flow-levelling channelsection 14 so as to turn the flow substantially 90 degrees.

The channel section 16 after the flow control plate 15 and connected tothe flow-levelling channel section 14 substantially at a 90-degree anglecomprises a two-part diffuser, the latter diffuser part 16 b of whichbeing in turn connected substantially at a 90-degree angle to a suctionbox 17 that is connected to the suction opening 10 of the second fanhousing 6.

The cross-profile of the diffuser 16 increases towards the suction box17 in such a manner that its mouth 16 c corresponds to the cross-profileof the suction box 17.

The above description of the invention is only intended to illustratethe basic idea of the invention. A person skilled in the art mayimplement the details of the invention in a variety of alternative wayswithin the scope of the attached claims.

1. A high-pressure fan comprising an electric motor provided with ashaft that passes through said motor; first and second blade wheels madesubstantially of a carbon fibre-based composite material, arranged onboth sides of the electric motor and mounted directly on said shaft;first and second fan housings surrounding the first and second bladewheels respectively; and an intermediate channel which connects apressure opening of the first fan housing to a suction opening of thesecond fan housing; the intermediate channel being integrated into abase structure of the high-pressure fan and located substantially belowsaid electric motor and said blade wheels, wherein said intermediatechannel has a pressure opening, a straight channel section for levellingthe flow, a length of the section corresponding substantially to alength of a long side of said pressure opening of said first fanhousing, and further wherein a flow control plate is arranged at one endand in a middle portion of the straight channel section so as to turnflow of air substantially 90 degrees.
 2. A high-pressure fan as claimedin claim 1, wherein a portion of said channel section downstream of theflow control plate and connected to the flow-levelling channel sectionsubstantially at a 90-degree angle comprises a two-part diffuser, adownstream part of which being in turn connected substantially at a90-degree angle to a suction box that is connected to the suctionopening of the second fan housing.